Vapor electric discharge device



Aug. 30, 1938. TONKS 2,128,862

VAPOR ELECTRIC DISCHARGE DEVICE Filed July 16, 1936 Inventor: LewiTonks,

by W i.

is A torney.

Patented Aug. 30, 1938 PATENT OFFICE VAPOR ELECTRIC DISCHARGE DEVICELewi Tonks, Schenectady, N. Y., assignor to General Electric Company, acorporation of New York Application July 16,

8 Claims.

The present invention relates to vapor electric discharge devices, andmore particularly to improved means for controlling the operation ofsuch devices.

In my copending application, Serial No. 90,867,

filed July 13, 1936, and also assigned to the General Electric Company,I have described and claimed an improved means for anchoring the cathodespot of a pool-type discharge device on a rigid relatively invariablesurface.

It is an object of the present invention to provide in connection withsuch a spot-anchoring device means whereby the properties of the devicemay be advantageously utilized in controlling the initiation of an arcdischarge.

A further object of the invention consists in the combination with apool-type discharge device having a cathode spot-anchoring means of anexcitation circuit which is operable intermittently to efiectinstantaneous control of the device.

The features of novelty which I desire to protect herein are pointed outwith particularity in the appended claims. The invention itself,however, both with respect to its construction and mode of operation,together withfurther objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the drawing, in which Figs.

1 and 2 show in front and side elevation respectively a particular modeof application of the invention, and Fig. 3 shows a preferred circuitarrangement suitable for the effective utilization of the dischargedevice of Fig. 1.

3.", Referring particularly to Figs. 1 and 2 I have illustrated adischarge device in which a cathode spot-anchoring means may beadvantageously used in connection with means for controlling theinitiation of a discharge. As shown, this device comprises an envelope lcontaining an anode 2, for example of steel, a mercury pool cathode 3and a spot-anchor l. The anchor 4 is preferably constituted of thematerial described in my aforementioned application, Serial No. 90,867.

The material therein described comprises carburized cohering particlesof a metal of the group consisting of tantalum, tungsten and molybdenum,such particles being so combined as to produce a porous wick-likestructure. These materials may be wet with mercury in various ways,

for example by heating to an elevated temperature and plunging below themercury surface in the presence of hydrogen, or of an inert atmosphere.After once being completely immersed and impregnated with mercury, theyhave the 1936, Serial No. 90,868

property of retaining their wetness under varying conditions and willresist disintegration even after a considerable period of use in adischarge device. As a result of the porosity of the anchoring body andof its ability to be wet by mercury, it acts as a wick and developssuflicient capillarity to draw mercury from the cathode pool 3 to itsupper exposed surface which thus retains a thin film of mercury duringthe operation of the device. This mercury is effectively immobilized inthe sense of being unable to vary in level or position after the mannerof the main cathode surface. Arranged in fixed relation to the uppersurface of the anchor l I provide a sparking electrode 8 comprising, inthis instance, a tapered strip of refractory conducting material, forexample, molybdenum having one edge thereof directed toward the uppersurface of the anchor. The various electrodes are furnished withsuitable lead-in conductors 8, 9 and Ill, respectively, for impressingdesired potentials thereon.

The mode of utilization of a tube of this construction may be understoodby reference to Fig. 3 in which I have illustrated a regulating circuitadapted to modify the characteristics of. an alternating potentialsupplied from an input source It to a load which is to be connected atH. Regulation is accomplished by means of two discharge devices I and Icorresponding to the device described in connection with Fig. 1. Theseare connected in a manner well understood in the art, so that one isadapted to conduct during positive half cycles, while the other iscapable of conducting during negative half cycles. By means more fullydescribed in the following, each device may be controlled so that it isconductive during only a desired portion of a half cycle rather than afull half cycle. In this way the amount of power transmitted can be re uated within close limits.

The control system for the two discharge devices is supplied withpotential from the secondary of a phase-shifting transformer IQ of knownconstruction, which potential is impressed between the various sparkingelectrodes and the corresponding anchoring bodies by means of a suitablestep-up transformer 20. Referring particularly to the circuit associatedwith the discharge device I, the phase angle of the transformer I! is soadjusted that the plates of the condenser C connected to the sparkingelectrode 6 are cyclically charged through the resistor 23 in desiredrelation to the cyclical variations in the potential impressed betweenthe anode and the cathode of the device. The adjustment is such that thecondenser potential attains a value sufficient to produce a sparkingdischarge through the resistor R and from the electrode 8 to the anchor4 at a desired moment during the period when the anode 2 is positivewith respect to the cathode 3. I have found it to be highly desirablefor consistent operation that the sparking discharge be non-oscillatoryand comprise a unidirectional pulse of current proceeding in thepositive sense from the sparking electrode to the anchor body. Thiscondition will be sufflciently fulfilled in the circuit of Fig. 3 whenthe resistance of 23 is roughly at least ten times the resistance of Rand when the quantity iL/RFC is less than about 4 where L is theself-inductance of the sparking circuit in henries and R and C are thevalues of the resistance R in ohms and of the capacity of condenser C infarads respectively. Otherwise expressed, the inductance of the circuitshould be less than the product of the capacitance of the condenser Cand the square of the resistance of the resistor R. It is also desirablefor consistent operation that the peak current in the spark exceedapproximately one-half ampere and that the quantities L, C and R shouldbe so proportioned with respect to the breakdown voltage of the sparkgap that this condition is attained.

It will be understood that the sparking circuit associated with thedischarge device I is identical with that just described, except thatthe sparking discharge is timed to occur substantially out-of-phase withthat of the discharge device I. In both these circuits, although thecharging of the condenser C has been described as being accomplishedthrough the resistor 23, other current limiting devices such, forexample, as a thermionic tube of controllable unidirectionalconductivity may be used for this purpose.

In the foregoing I have referred to mercury as an exemplary cathodematerial. It should be understood, however, that other liquid metals,for example, gallium, or sodium or cadmium when in the liquid phase mayalternatively be employed.

Furthermore, while I have shown particular structural embodiments of myinvention, it will be understood that many modifications may be made bythose skilled in the art without departing from the invention, and I aimby the appended claims to cover all such modifications as fall withinthe true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an electrical discharge device, an anode, a rigid body having asurface adapted to substantially immobilize a quantity of mercurythereon, means for supplying mercury to said surface, a sparkingelectrode in fixed spaced relation to said surface, means for impressinga difi'erence of potential between said anode and said body, anenergizing circuit for producing a spark discharge between saidelectrode and said surface, and means associated with said circuit forcausing such discharge to be non-oscillatory.

2. In an electrical discharge device, an anode, a rigid body having asurface adapted substantially to immobilize a quantity of mercurythereon, means supplying mercury to said surface, a sparking electrodein fixed spaced relation to said surface, means for impressing acyclically varying discharge potential between said anode and said body,means including an energy source for cyclically creating a sparkdischarge from said electrode to said surface, said last-named meansbeing operable in predetermined relation to the variations of saiddischarge potential and means in circuit with said energy source forcausing said discharge to be of a non-oscillatory character.

3. In an electrical discharge device, an anode, a rigid body having asurface adapted to retain a quantity of mercury thereon, means forsupplying mercury to said surface, a sparking electrode in fixedrelation to said surface, means for impressing a difference of potentialbetween said anode and said body, means for creating a discharge betweensaid electrode and said surface, said means comprising a condenser, acircuit including a resistor for impressing the voltage of saidcondenser between said electrode and said surface, and means forcharging said condenser, said condenser and said resistor being sopropori'ioned with respect to the inductance of said circuit as to causesaid discharge to be non-oscillatory.

4. In an electrical discharge device, an anode, a cathode comprising arigid body having a surface adapted to retain a quantity of mercurythereon, and means for supplying mercury to said surface, a sparkingelectrode in fixed relation to said surface, means for impressing adifference of potential between said anode and said cathode, means forcreating a discharge between said electrode and said surface, said meanscomprising a condenser, a circuit including a resistor for impressingthe voltage of said condenser between said electrode and said surface,and means for charging said condenser, the inductance of said circuitbeing less than the product of the capacitance of said condenser and thesquare of the resistance of said resistor.

5. In an electrical discharge device, an anode, a mercury pool cathodeincluding a cathode spotfixing body, a sparking electrode in fixedrelation to said body, means for impressing a difference of potentialbetween said anode and said cathode,

and means for creating a non-oscillatory discharge between saidelectrode and said body which discharge has a current intensity inexcess of about 0.5 amperes.

6. In combination, an anode, a cathode including a pool of liquidcathode material and a rigid body having a switch-likedischarge-receiving surface which is adapted to retain a thin film ofliquid cathode material thereon, said surface being appreciably abovethe normal level of the pool, means supplying cathode material to saidsurface to maintain said film, a sparking electrode positioned at afixed sparking distance from said surface, means for energizing saidanode and cathode, and means including said sparking electrode forcontrolling in a desired manner the initiation of a discharge betweenthe anode and cathode upon the application of a favorable potentialbetween them, said last named means comprising an energizing circuitoperable intermittently in response to a controlling infiuence to createa spark discharge between said electrode and said body.

7. In combination, an anode, a cathode including a pool of liquidcathode material, a porous wick-like body in contact with the cathodematerial and having an exposed surface appreciably above the normallevel of the pool, said body acting by caplllarity to maintain a film ofcathode material on said surface, a sparking electrode disposed at afixed distance from said surface, means for energizing said anode andcathode, and means including said sparking electrode for controlling ina desired manner the initiation of discharge between the anode andcathode upon CERTIFICATE OF CORRECTION Patent No. 2,128 ,862.

material on said surface, a sparking electrode disposed at a fixeddistance from said surface, means for impressing a cyclically varyingdischarge potential between the main anode and cathode, and means forcyclically creating a spark discharge between said sparking electrodeand said body, said last named means being operable in predeterminedrelation to the cyclical variations of said discharge potential.

LEWI TONKS.

August 30, 1958.

LEwI TONKS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 1 .7, claim 6, for "snitch-like" readwick-like; andthat the said Letters Patent shouldbe read with this correction thereinthat the same may conform to the record of the case in the Patentoffice.

Signed and sealed this 25th day of October, A. D. 1958.

(Seal) Henry Van Arsdale Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION Patent No. 2,128 ,862.

material on said surface, a sparking electrode disposed at a fixeddistance from said surface, means for impressing a cyclically varyingdischarge potential between the main anode and cathode, and means forcyclically creating a spark discharge between said sparking electrodeand said body, said last named means being operable in predeterminedrelation to the cyclical variations of said discharge potential.

LEWI TONKS.

August 30, 1958.

LEwI TONKS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 1 .7, claim 6, for "snitch-like" readwick-like; andthat the said Letters Patent shouldbe read with this correction thereinthat the same may conform to the record of the case in the Patentoffice.

Signed and sealed this 25th day of October, A. D. 1958.

(Seal) Henry Van Arsdale Acting Commissioner of Patents.

